There are navigation systems known in the related art that execute navigation operations by using map data recorded in recording media such as CD-ROM (see, for instance, patent reference literature 1). Such map data provided in recording media may be made available in separate versions each corresponding to a specific region, e.g., a Kanto region version, a Chubu region version and a Kinki region version.    Patent reference literature 1: Japanese Laid Open Patent Publication No. H8-292716